#!/usr/bin/env node
/* eslint-disable no-plusplus */
/**
 * skills/deploy/scripts/build-harness.mjs — build a local QA harness from a DA content page.
 *
 * The Step-10 visual-diff harness needs the content page's <main> with the
 * metadata block removed and absolute image URLs made local. Hand-rolling that
 * strip with a regex is fragile (the metadata block is nested div-in-div, so a
 * naive `…</div></div>` match stops a tag too early and leaves an orphan </div>
 * that corrupts the harness DOM — #46). This does it with balanced tag counting.
 *
 * Usage: node skills/deploy/scripts/build-harness.mjs <contentFile> <outHarness> [--root <dir>]
 *   e.g. node skills/deploy/scripts/build-harness.mjs content/snowflake-blocks/test-12.html qa/test-12.html
 *   --root <dir>  repo root the harness is served from (favicon detection;
 *                 default: cwd)
 *
 * Output: a full HTML doc loading /styles/styles.css + /scripts/scripts.js
 * (which imports aem.js, adds body.appear, and loads the sections — the same
 * boot as head.html), body = empty <header>/<footer> (the runtime's
 * loadHeader/loadFooter need the elements to exist, and loadLazy would die
 * before loading any section if <header> is missing) + <main> with metadata
 * removed and every absolute .../img/ (or http://localhost:PORT/img/)
 * <img src> rewritten root-relative.
 * The favicon link derives from what actually shipped (deploy Step 3
 * § Favicon is format-preserving — favicon.<ext>): exactly ONE link,
 * mirroring the icon href in <root>/head.html when present (that line is
 * what shipped), else the repo-root favicon.{ico,svg,png} that exists, or
 * `href="data:,"` when none does — zero favicon requests either way (probe
 * determinism, no guaranteed 404 per load).
 */
import { readFileSync, writeFileSync, existsSync } from 'fs';
import { join } from 'path';

// Return the index just past the </div> that closes the <div> starting at `start`.
function matchDivEnd(s, start) {
  const re = /<div\b|<\/div>/gi;
  re.lastIndex = start;
  let depth = 0;
  let m = re.exec(s);
  while (m) {
    if (m[0][1] === '/') { depth--; if (depth === 0) return m.index + m[0].length; } else depth++;
    m = re.exec(s);
  }
  return s.length;
}

const argv = process.argv.slice(2);
let root = process.cwd();
const pos = [];
for (let i = 0; i < argv.length; i++) {
  if (argv[i] === '--root') root = argv[++i];
  else pos.push(argv[i]);
}
const [inFile, outFile] = pos;
if (!inFile || !outFile) {
  process.stderr.write('usage: node skills/deploy/scripts/build-harness.mjs <contentFile> <outHarness> [--root <dir>]\n');
  process.exit(1);
}
let html = readFileSync(inFile, 'utf8');

// 1. extract <main>…</main>
const mm = html.match(/<main[\s\S]*?<\/main>/i);
let main = mm ? mm[0] : html;

// 2. remove the metadata section: the wrapper <div> two levels above class="metadata"
const metaAttr = main.indexOf('class="metadata"');
if (metaAttr >= 0) {
  const metaDiv = main.lastIndexOf('<div', metaAttr);
  const wrapDiv = main.lastIndexOf('<div', metaDiv - 1);
  const end = matchDivEnd(main, wrapDiv);
  main = (main.slice(0, wrapDiv) + main.slice(end)).replace(/\n\s*\n/g, '\n');
}

// 3. rewrite absolute image origins to root-relative /img/ so committed assets load
main = main
  .replace(/https?:\/\/[^"')\s]*?\/img\//gi, '/img/')
  .replace(/http:\/\/localhost:\d+\/img\//gi, '/img/');

// 4. sanity: no orphan leading close tag
const lead = main.replace(/<main[^>]*>/i, '').trimStart();
if (lead.startsWith('</div>')) {
  process.stderr.write('WARN: harness <main> starts with an orphan </div> — metadata strip mis-balanced.\n');
}

// 5. favicon: emit ONE link matching the favicon that actually shipped.
// Authority order: (a) the icon link deploy Step 3 § Favicon wrote into
// <root>/head.html — that href IS what ships, so mirror it (a bare
// existence probe would link a stale boilerplate favicon.ico even when the
// deploy shipped favicon.svg/png alongside it); (b) no head.html icon link →
// file existence, ico first (an ico-only site has no head.html line by
// design — /favicon.ico is the browser default); (c) nothing → the data:
// no-op keeps the harness at zero favicon requests (probe determinism, no
// guaranteed 404 per load).
let faviconLink = null;
const headFile = join(root, 'head.html');
if (existsSync(headFile)) {
  const head = readFileSync(headFile, 'utf8');
  const iconTag = (head.match(/<link\b[^>]*>/gi) || []).find((t) => /\brel=["'][^"']*icon[^"']*["']/i.test(t));
  const href = iconTag && iconTag.match(/\bhref=["']([^"']+)["']/i);
  if (href) faviconLink = `<link rel="icon" href="${href[1]}">`;
}
if (!faviconLink) {
  const faviconExt = ['ico', 'svg', 'png'].find((e) => existsSync(join(root, `favicon.${e}`)));
  faviconLink = faviconExt ? `<link rel="icon" href="/favicon.${faviconExt}">` : '<link rel="icon" href="data:,">';
}

const doc = `<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><title>QA harness</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="/styles/styles.css">
<script src="/scripts/scripts.js" type="module"></script>
${faviconLink}</head>
<body>
<header></header>
${main}
<footer></footer>
</body></html>`;
writeFileSync(outFile, doc);
process.stdout.write(`harness written: ${outFile} (${doc.length} bytes)\n`);